package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collections;
import java.util.concurrent.TimeUnit;

public class RedisLock implements ILock{
    private final StringRedisTemplate stringRedisTemplate;

    private final String name;

    private static final String KEY_PREFIX = "lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString(true) + "-";
    private static final DefaultRedisScript<Long> LUA_SCRIPT;

    static {
        LUA_SCRIPT = new DefaultRedisScript<>();
        LUA_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        LUA_SCRIPT.setResultType(Long.class);
    }

    public RedisLock(String name, StringRedisTemplate stringRedisTemplate) {
        this.name = name;
        this.stringRedisTemplate = stringRedisTemplate;
    }

    @Override
    public boolean tryLock(long timeoutSec) {
        // 获取线程标识
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        // 获取锁
        Boolean success = stringRedisTemplate.opsForValue().
                setIfAbsent(KEY_PREFIX + name, threadId, timeoutSec, TimeUnit.SECONDS);

        return Boolean.TRUE.equals(success);
    }

    @Override
    public void unLock() {
        // 获取线程标识
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        // 调用Lua脚本,保证原子性（判断和删除）
        stringRedisTemplate.execute(LUA_SCRIPT, Collections.singletonList(KEY_PREFIX + name), threadId);
    }
}
